Paper clips are generally used as expendable items to either temporarily attach papers or as indexing markers.
Use of the common paper clip presents a number of problems. In use, the two loops of the common paper clip must be digitally manipulated and manually spread so that papers can then be inserted between the loops. The common paper clip does not work well for any significant thickness of paper, being difficult to apply, and once applied is physically deformed, in the process, such that it cannot be reused without being deliberately and correctionally rebent by the user. Further, when used with any significant thickness of paper, the loops of the common paper clip torque on their long axises such that the clip will not lie flat on the papers and will simultaneously protrude from the plane of the papers on either side. This also results in the sharp ends of the legs digging into the papers causing damage. More damage will usually occur during removal of the clip as the clip is dragged ever deeper into the paper.
Also, because the loops of the paper clip are being spread apart, there is a tendency for the common paper clip to try to close by forcefully ejecting off of a thick group of papers, thereby presenting a very real threat to the user, who may be struck in the eye.
Apart from their use in temporarily attaching papers, paper clips are also used as indexing markers, as when they are placed on documents to indicate an area to be read or signed, or as when used to bracket a significant chapter within a book. The common paper clip is however, poorly designed for this purpose When used within a book, the pages of the book are damaged when the book is closed over the rotated legs of the clip from both the kinking of the pages and the driving of the bare ends of the common paper clip into the page. When used to index important papers the visible end is relatively small, such that it is not always clearly visible when the book is closed. Further, the documents may be damaged upon removal of the clips.
In addition to the common paper clip, other clips have been proposed, such as disclosed in the accompanying prior art statement. Such clips suffer from one or more of the following disadvantages: They will not accommodate any significantly thickness of papers; tend to forcefully eject from a thick group of papers; do not lie flat; require finger manipulation and spreading of the legs for application; are easily deformed; or are expensive.
The Acco clamp shown in the Prior Art Statement, while appearing to have some resemblance to the present invention upon casual inspection, will be found to be heavy, bulky and without advantage, unnecessarily complex. It should be observed that the clamp is constructed such that a pair of looped legs extend from the top spine at a 60 degree angle, and in completing their long journeys cross each other four times. This produces an out of plane angular deformity such that this device cannot lie flat when applied to any significant thickness of papers because the legs deploy and rotate out of the surface plane of the papers. As a further result of the legs crossing each other no less than four times and therefore, contacting the contained papers in at least as many places, and because of the rigidity of the overall construction, damage to the papers is common with its use.
Other clips commonly referred to as "bulldog" clamps, are in actuality just that a clamp, and are for the purpose of holding together very large stacks of papers. These clamps are extremely heavy, bulky and relatively expensive as compared to the more common paper clip. Due to the above limitations, they are generally found to be of limited use and are not appropriate for use in the mail. Furthermore, they have little merit as indexing or place marker devices.